Solvothermal Preparation And Microwave Absorption Of Three-dimensional Magnetic Graphene

With the advancement of science and technology,the electronic information industry,medical industry and radar technology are developing rapidly,greatly enriching people's lives,but excessive electromagnetic wave radiation has also brought serious electromagnetic pollution problems,which not only affects the application of electronic equipment,but also causes harm to human health and ecological environment.In order to reduce electromagnetic pollution,in addition to properly designing the circuit,microwave absorption or shielding is also one of the common methods to prevent electromagnetic interference.Therefore,high-performance microwave absorbing materials of"light weight,small thickness,strong absorption and high effective bandwidth"have also attracted increasing attention.In the selection of materials,graphene has become the first choice of new light-wave absorbing materials due to its ultra-high specific surface area,special microstructure,and strong chemical stability.However,the carbon material has a large dielectric constant,which is not conducive to impedance matching,resulting in poor absorbing performance.At the same time,from a nano perspective,carbon materials are prone to agglomeration during the preparation process.Scientists at home and abroad have conducted a lot of research on the above issues,and concluded that by preparing graphene-based composite materials,the purpose of adjusting electromagnetic parameters,improving the degree of impedance matching and improving the degree of dispersion can be achieved,thereby preparing high-performance,multifunctional composite Type absorbing material.Therefore,in this paper,different magnetic metal particles are supported on graphene,and magnetic porous three-dimensional graphene-based composite wave absorbing materials have been successfully prepared,and the wave absorbing mechanism of the materials has been explored.The main contents are as follows:In this experiment,flaky graphite was used as a raw material,and graphene oxide was prepared by an improved Hummers method.Based on graphene oxide and acetylacetone complex,a series of magnetic porous three-dimensional graphene nanocomposites were prepared by solvothermal method Materials?RGO@Ni?RGO@Fe₃O₄?RGO@Co/CoO?.Due to the combined effect of the porous structure and multiple loss mechanisms,magnetic porous3D graphene composites exhibit excellent electromagnetic wave absorption performance in terms of minimum reflection loss(RL_min)and maximum effective absorption bandwidth?EAB?.The research shows that the minimum reflection loss value(RL_min)of RGO@Ni nanocomposite material at the thickness of 2.2mm is-61.2 dB,and the EAB r is 6.6GHz?10.5-17.1 GHz?at the thickness of 2.5mm.The super paramagnetic RGO@Fe₃O₄ nanocomposite at2.1mm has a minimum reflection loss of-65.7 dB and an EAB of 6.0 GHz.More interestingly,the material can still maintain excellent electromagnetic wave absorption performance after acid treatment.For RGO@Co/CoO nanocomposites were synthesized by solvothermal and high-temperature calcination.when the calcination temperatures are 350°C,500°C,and 650°C,respectively,RGO@CoO?S350?,face-centered cubic RGO@Co?S500?,biphasic RGO@Co nanocomposite?S650?were successfully prepared.When S500 is only 10%filled,the minimum reflection loss value of the material at a thickness of 2.5 mm is-74.5 dB and the EAB is 6.1 GHz.In view of the above advantages,we believe that our results will be synthetic porous magnetic graphene composites Provide new ideas.